1. Field of the Invention
This invention relates to an antenna system having multiple reflector antenna units in tandem and more particularly to such a system suitable in mobile installations for transmitting signals to and receiving signals from a satellite.
2. Description of the Related Art
Prior art antennas used in mobile installations for communications with satellites generally utilize a single feed unit which has a parabolic reflector. In order to attain the needed gain a reflector of fairly large dimensions is needed. The installation of a large reflector on a vehicle poses problems from the point of view of the air resistance when the vehicle is moving as well as the limited space available on most vehicles.
To Applicant""s knowledge, no prior art parabolic reflector antenna systems have been developed to cope with this problem. Low profile hemispherical Luneberg lens systems employing multiple antenna units are described in U.S. Pat. No. 5,781,163 issued Jul. 14, 1998 to Ricardi, et al. and assigned to Datron/Transco,Inc., the assignee of the present application and U.S. Pat. No. 3,386,099 issued May 28, 1968 to Walter, et al. Both of these patents are directed to Luneberg lens antenna systems and no reference is made to antennas employing parabolic reflectors.
The device of the present invention is an improvement over the prior art in that it provides a less bulky antenna system having lower air resistance which is particularly suitable for use on vehicles. Multiple parabolic reflector antennas are joined together on a common base and are driven in tandem to desired positions both in azimuth and elevation by a common drive unit. Similar antenna units are mounted adjacent to each other and directed in the same direction for receiving and transmitting signals from and to a satellite. The signals from each antenna unit are phase shifted as needed in a combiner unit which combines such signals in-phase with each other. In this manner, high gain is achieved without the need for a single large diameter reflector.
It is therefore an object of this invention to provide an improved parabolic reflector antenna system for use on a vehicle which can be used to communicate with a satellite;
It is a further object of this invention to provide an antenna system employing a parabolic reflector having less bulk and providing less air resistance than prior art such systems;
Other objects of the invention will become apparent in view of the following description taken in connection with the accompanying drawings.